1. Field of the Invention
The present invention relates to a high-powered lighting assembly utilizing a solid-state thermoelectric cooling system for primary use in theatrical or architectural lighting fixtures. More specifically, the present invention relates to a lighting assembly having a continuous sealable thermal barrier and an active closed-loop refrigeration system employing a Peltier-effect thermo-electric module(s) (hereinafter TEM(s)).
2. Description of the Related Art
With the emergence of increasingly higher-powered Light Emitting Diodes (LED(s)) in lighting arrays, and their use in theatrical and architectural illumination applications, there has been a corresponding increase in heat generation concerns.
Specifically, as higher power LED(s) are used, and as higher concentrations of LED(s) are used, the heat generated detrimentally affects unit life span, and reduces unit operational efficiency.
As both high power LED(s) and high concentrations of LED(s) are frequently used in architectural and theatrical lighting fixtures, and since architectural and theatrical end users are particularly sensitive to unit degradation, there has been a growing need to supply high quality LED displays which do not degrade in continual use.
Prior techniques of cooling LEDs in architectural and theatrical lighting fixtures involved mounting the LED(s) in a manner which thermally connected the LED(s) directly to some form of heat spreading plate, which was then mounted in contact with the housing of the lighting assembly itself. Thereafter, the lighting housing operated to dissipate the heat into the surrounding ambient atmosphere at a rate dependant upon the ambient atmospheric conditions.
In high use and in demanding situations, the thermal transfer from the LED(s), through the thermally connected heat spreading plate to the housing is insufficient to maintain a desirable LED temperature. Common cures to undesirably thermal buildup thereafter employ the use of fans, cooling fins, spacing assemblies, etc. to reduce housing temperature. Unfortunately, thermal back-flow may occur as a housing is heated by the ambient atmosphere beyond an optimal point which allows thermal conduction back to the heat spreading plate. In such situations, rapid LED degradation occurs and unit efficiency drops.
The above techniques for thermal removal have the common disadvantage of using direct passive conduction and convection heat transfer from the LED(s) to the heat sink or heat spreading plate and thereafter to the housing. The passive nature of these techniques limits the cooled temperature of the LED(s) to at or near an ambient atmospheric temperature. Since the units are often in close conjunction or are retained in decorative housings, passive heat transfer and thermal back-flow rapidly reduce cooling efficiency.
The Peltier effect is well known by those skilled in the related arts and provides an active solid-state thermoelectric cooling function from a cool side to a hot side. The cool side is commonly placed against a surface or substrate which requires cooling. For example, the back surface of an LED assembly. The hot side is commonly placed against a surface or substrate which absorbs the transferred thermal energy and transfers it through conduction to a heat spreading plate.
The Peltier effect is one of several well known thermo-electric effects. Others are the Seebeck effect, the Thompson effect, and the Nernst-Ettinghausen effect. Through the utilization of these thermo-electric effects, thermal transfer from a cool side to a hot side can be controlled by controlling a current supplied to the thermo-electric effect.
Unfortunately, conventional constructions substantially negate the optimal use of an active cooling device by directly or indirectly connecting an LED or light array to a housing or heat spreading plate in a manner which allows thermal back flow to the lighting array through either thermal conduction or convection mechanisms.
Conventional lighting assembly constructions also fail to provide an effective control loop for an active cooling device through non-optimal location of thermal sensors, lack of thermal sensors, and ineffective positioning for the cooling device itself resulting in non-uniform cooling.